


Big Hero 6: Anthro Boys

by eltigre221



Category: Big Hero 6 (2014)
Genre: AU, Alternate Universe, Anthro humans, Consexual Sex, F/M, Fred shouldn't play with science, Hidashi all the way, Incest, M/M, Sibling Incest, fluffiness ahoy, hidashi, movie plot still happens, older!Hiro, smut in later chapters
Language: English
Status: In-Progress
Published: 2015-07-03
Updated: 2015-07-11
Packaged: 2018-04-07 11:36:00
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 4,189
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/4261884
Author URL: https://archiveofourown.org/users/eltigre221/pseuds/eltigre221
Summary: <blockquote class="userstuff">
              <p>All Tadashi Hamada wanted to do was to get his baby brother enrolled into SFIT. He didn't think that something horrible would happen just by bringing his baby brother into the robotics lab. He was so wrong, but then again, he wouldn't be where he is now, if he hadn't brought his brother with him to the Nerd Lab.</p>
            </blockquote>





	1. Prelude Jail Sucks

**Summary for the Chapter:**

> Title says all.

**Prelude**

**Jail Sucks**

Tadashi glared at his little brother from across the hall. They had both been found by the cops leaving the bot fight. Well Hiro was at the botfight and would’ve been hurt hadn’t Tadashi arrived when he did. So, in trying to get his brother safely out, they had an argument about his bot fighting habit. Sadly they ran right into the cops when Hiro had the money out and right in front of him.

Now they were both in jail and it sucked. Hiro, being a minor at age 16, was stuck in a cell all by himself, and Tadashi being 22 was jammed into the other cell… with all the other adult males that had been at the bot fight. They had no room what so ever.

Oh how Tadashi wished that getting arrested and thrown into jail temporarily would be the worst thing that has happened to him, rather than what was about to happen to him and Hiro.  



	2. It's Not Science

**Summary for the Chapter:**

> Fred really shouldn't be allowed to make things.

**Chapter 1**

**It’s Not Science**

Tadashi grinned as he pulled up to his beloved college. He ignored Hiro’s jibe about going to the bot fight, as if he’d actually take him to one after they just got out of jail. Tadashi rolled the two of them up to his lab, the Ishioka Robotics Lab. He smiled, taking off his helmet, and told Hiro he needed to grab something.

It didn’t take long for them to get to the robotics lab, they also happened to pass by a couple of students who were there late tonight. “Relax you big baby, and besides you’ve never seen my lab before.” Hiro complained about seeing his ‘nerd’ lab, but Tadashi just grinned and watched everything unfold.

Hiro gazing at all the tech around him, and then he walked over and checked out Gogo’s bike. She did almost run him over when he walked inside. “Hey Gogo, this is my little brother, Hiro.”

Gogo showed him her project, before throwing the back wheel into the massive trash bin with all of her other rejects. After she stalked off, Hiro was attracted to the sound of Wasabi working on his own project. He would’ve walked straight into the lasers, hadn’t Wasabi stopped him.

“Hey Wasabi, this is my brother Hiro.” Tadashi introduced his little brother to the large and muscular African American male.

Wasabi smiled and showed Hiro his own project of laser induced plasma. Their meeting went well, until Gogo came over and stole one of Wasabi’s wrenches, and ended up making a mess of his once very clean and organized work table. As he ran to catch up to Gogo, Honey Lemon ran over attempting to make another chemical reaction.

She grinned and kissed both of Hiro’s cheeks before showing him her latest chemical reaction. When she was done and covered in pink Tadashi came over, grinning at his tall blonde friend. “Not bad Honey Lemon,” he commented.

Hiro asked about the names, and everyone heard Wasabi complaining about the wasabi on his shirt. Tadashi chuckled breathlessly and looked back at Hiro and explained. “Fred is the one who comes up with the nicknames.”

Speak of the devil; he appeared right behind Hiro, nearly giving the poor prepubescent teen a heart attack. Fred went on to explain about how he wanted some of his science stuff to be real. Tadashi just smiled and watched as his friends went about their work, he was about to take Hiro into his own lab, when Fred came up to them.

“Hey Tadashi, can I show you and Hiro something I’ve been working on.” Fred asked his oldest friend.

Tadashi was confused, but he looked down at Hiro who seemed to be interested in whatever it was that Fred had made. “Well I guess it couldn’t hurt to see it before I show Hiro my own project.”

Fred grinned and dragged the brothers over to a lab that was vacant. He closed the door behind them, and went over to grab something that was in a brown box. From the looks of it, it was a purple, black, and blue gun of sorts; it was slightly bulky as well.

“So what does it do?” Hiro asked. He took a long look at the strange gun.

“Well you know how I wanted Honey to create a formula to turn me into a lizard man?” Fred asked the brothers, both nodded.

“Well, a former student made this for me said he wanted a unique challenge, so he made the next best thing.” Fred stated while holding up the gun. “This thing can turn you into an Anthro of any animal in existence.”

Hiro looked interested, but Tadashi was concerned. “Is there a way to reverse it, if the person doesn’t want to be an Anthro?” Tadashi asked.

Fred sadly shook his head, “No, the guy died before he could add on a reverse switch.”

Both brothers looked at the gun and felt a little sad for Fred. They knew he wanted to test it, but if there was no way to reverse the process. Hiro soon smiled though and said, “Well, you can test it on me if you want.”

Tadashi gave Hiro an alarmed look, while Fred looked a little excited. “Do you mean that?” Fred asked, sounding very hopeful.

“Sure, I mean what harm could it do,” Hiro stated with a smile. “I mean all I’ll get is some ears and a tail right, depending on what animal I am.” He said it in such a nonchalant manner, that Tadashi just let out a breathy sigh and stated.

“Test it on me too. I’m not letting this knucklehead get into any more trouble alone.” He smirked at the shorter male. This earned himself a glare from Hiro, not that he was surprised, and a warm beaming grin from Fred, the mascot happy that the brothers wanted to try out his invention.

He started up the machine, being careful with it as he set it up. Tadashi was worried, but knew the odds of the machine working would be very slim. So he waited patiently with Hiro. He idly wondered what animal he’d be if he was an Anthro. Fred charged up the ray, set everything up the way it was supposed to be, took aim and fired. The room and the rest of the campus were encased in a massive bright white to purple light.

During the bright light, the gun exploded in Fred’s hands, he was fine, but what he didn’t know is that what was once ‘isn’t science,’ sadly has become science.


	3. What Did You Do?

**Summary for the Chapter:**

> Aftermath

**Chapter 2**

**What Did You Do?**

After the light subsided, everyone in SFIT groaned, or in the case of two brothers, grunted. Everyone had to blink quite a few times to get their respective vision straight. Gogo was the first one to wake up, or rather gain some of her sight back. She looked around and saw nothing dangerous had happened thankfully, but it did look like everyone’s robotic experiments had all shorted out. Even her own, since the wheels for her bike were on the floor.

She saw Honey Lemon and Wasabi starting to stand after their brief tumbles to the floor. It was a good thing Honey wasn’t dealing with chemicals when she fell, otherwise something bad might’ve happened. “Is everyone alright?” Gogo asked everyone.

“I’ll live,” Wasabi groaned out, since apparently some of his tools had somehow landed on him when he had been organizing them.

“What caused that explosion of light?” Honey asked as she got up.

“Well we know Tadashi wasn’t working on anything, Hiro doesn’t have any equipment here, and Fred.” Wasabi began, but paused as soon as he said Fred’s name.

“Please tell me he didn’t,” Honey whispered.

“You know he did,” Gogo stated calmly. The three remaining members of the group of friends went to go and confront their mascot/comic nerd friend. They arrived at the lab that Fred, Tadashi and Hiro had all gone into.

Gogo knocked, to let Fred know they were outside, “Fred we’re coming in.”

They opened the door, and stared at the brothers whom were now sitting half-naked in the middle of the room. But they weren’t staring at them because they were half-naked, but because of the fact that the brothers now have an extra pair of ears atop their heads, and tails coming out of their tail bones. Their pupils were also slit now, and Fred was just staring at the brothers in awed shock. “It worked,” he whispered in shock.

“Uhh Fred, what exactly worked?” Honey asked after a brief pause.

“And on a more important note, WHAT DID YOU DO?” Wasabi demanded from the Kaiju enthusiast.

Before the Kaiju enthusiast could tell them what had happened, one of the professors came up behind them and asked. “Do any of you know what that bright light was?” The group of four humans turned around to see the aged professor in the doorway, it was Professor Callahan.

“It was the anthro ray gun, Alexander Benton made for me.” Fred told the professor while still staring at the new anthro boys.

“Wait, Alexander Benton, the guy who was killed by Yama’s gang, Alexander Benton?” Gogo demanded when she heard Fred say who made the supposed gun.

“Yeah, that’s him, he made me an anthro ray gun before he died, but he died before he could put on a reverse switch.” Fred explained to the group behind him. “Well the good news is that it worked, but the bad news is that it can’t be undone.”

“What can’t be undone?” Professor Callaghan asked the mascot.

Fred just pointed in front of him, and the group fully entered to get a much better look at the brothers. Hiro was seated on the floor looking up at them in unmasked curiosity and what looked like a bit of fear. His new anthro feline ears could barely be seen atop his head, since his wild mop of hair hid them so well, but his human ears were still there, even if they were hard to see. There was a pitch black feline tail coming out, it wasn’t really moving around, but they could see it twitching now and then.

Right next to him, on his hand and knees, was Tadashi; he was shirtless, just like his brother. His hat was knocked off during the explosion, but from the looks of the shredded fabric on the floor, the brother’s shirts were destroyed during their transformation apparently. And from the black feline ears atop Tadashi’s head, and the black feline tail coming out of his tail bone, he was an anthro now as well. But his slit pupil eyes were somehow staring at them in caution and mistrust for some reason.

Everyone was just staring at the brothers, when all of the sudden, Tadashi’s eyes narrowed and he snarled loudly at the group of six. He crouched down into a defensive stance in front of Hiro. His arms and legs were shifting and changing into paws, fur was growing up to his forearms and thighs, his fingernails were becoming powerful claws, and his canines were becoming sharper and stronger.

He looked absolutely feral, everyone was very afraid of the now terrifying Tadashi Hamada. “Why don’t we leave them alone for a little bit huh?” Wasabi suggested and everyone else silently agreed.

“Let’s get out slowly, I don’t wanna be Hamada chow,” Fred said. Gogo didn’t want to go slow, but right now she wasn’t objecting to anything at all.

Everyone soon was outside of the room, and closed the door behind them. Leaving the anthro Hamada’s inside and all alone. “Okay, what the hell was that about?” Gogo demanded/asked the group.

“Tadashi probably thought one of us was a threat to Hiro and got defensive.” Fred suggested.

“That’s an understatement, but are they gonna be okay?” Honey muttered at first, before asking.

“I’ve got no idea, besides we don’t even know what animal they are. I mean it’s kinda obvious they’ve felines, but what feline species specifically?” Fred stated. He was the calmest out of the entire group right now, and surprisingly the most knowledgeable.

“Does anyone have any idea what we’re gonna do about the two wild cats we’ve got locked in the lab?” Wasabi demanded, his voice getting very strained and sounding almost hysterical.

“We could use catnip to keep them calm,” Gogo suggested.

“Would that even work?” Wasabi countered.

“What’re we gonna tell their Aunt?” Honey Lemon added.

Everyone turned to look at the blond chemist, their eyes wide. It hadn’t occurred to them yet how they were going to explain to Tadashi and Hiro’s loving, guardian that her nephews were now half cat. When she’d find out, she’d stress eat so bad, she might gain about ten pounds.

“How do we tell her, this isn’t something you just bring up in casual conversation,” Gogo told them sarcastically.

“Is it even possible to turn them back to normal, or at least some form of normal?” Honey Lemon asked aloud. Wondering if they could turn the brothers back into humans, or at least find a way to make them more human than they were right now.

“Probably not,” Fred said as he went to grab a few of his items from his little corner of the nerd lab. “The gun exploded, no one was hurt thankfully, besides I’ve got no idea how that machine even worked.”

“Then why did you think it was a good idea to fire it at Tadashi and his younger brother?” Professor Callaghan asked the mascot.

“They volunteered to be test subjects.” Fred told him.

“I don’t think they expected it to work though Fred,” Honey told him softly.

“Yeah, you’re probably right, besides I didn’t even know if it would work. It hadn’t been tested before and the only ‘test subjects’ are Tadashi and Hiro.” Fred told them, air quoting test subjects, because if they knew it worked. Well they wouldn’t have used the gun in the first place.

Before everyone could get pissed at him, the door to the lab that Hiro and Tadashi had been inside opened up. The group turned to see Tadashi standing there. No shirt, both ears visible, and his tail lashing in annoyance. “Why were we locked in the lab?”


	4. Aunt Cass and Surprises

**Summary for the Chapter:**

> Things just got worse.

**Chapter 3**

**Aunt Cass and Surprises**

Everyone just stared at the shirtless Hamada as he stood there and partially glared at his friends and professor. His feline tail was lashing behind him; or rather his panther tail was lashing behind him. While he had been in the lab, after snapping out of whatever trance he was in. He looked up what animal he and Hiro were. Since for some reason, they were both the same species of animal. Everyone was staring at him, whether it was in regards to his ears or tail, or slit pupils he didn’t know. He simply kept his gaze steady as he watched his friends and professor all sweat as he stared them down.

“Are you going to answer my question or not?” Tadashi demanded of them.

Everyone flinched back, either at snapping out of their shock or from the possible tone of Tadashi’s voice. “Sorry dude, but you were snarling at us and your arms had changed into paws and claws and you looked about ready to attack to be honest.” Fred informed the elder Hamada brother.

Tadashi didn’t look like he really believed them, but he just nodded in acceptance after a few minutes. “Alright, I need to get something from my lab; then I’m heading home with Hiro.” He told them, before heading over to his lab. He ignored the gawking stared of the other students still in the lab. Most likely staring at his extra appendages, but he just ignored them and went into his lab to grab the three items he needed. After grabbing the items, he shut his lab down and then locked up.

He came out wearing a long sleeved shirt that he kept in his lab for the occasions he spent the night after working too long a project. He always kept at least two sets of clothes to change into, but took them home when they had gotten dirty and then replaced them. In his arms, were Baymax’s red traveling case/charging station and a second shirt, he went into the other lab where Hiro still was. After grabbing his brother, now wearing his older brother’s shirt, the siblings left the lab and headed home.

**BH6-BH6-BH6-BH6**

The ride home, for the most part, was very uneventful, other than the brothers getting annoyed that their second ears were getting squished by their helmets. But once they got home, they knew their Aunt wasn’t going to take this well, not at all.

Tadashi grabbed Baymax, and the two brothers had an easy time sneaking up to their shared bedroom. Or so it seemed, Aunt Cass cornered them when they tried to head up the stairs to their bedroom. How she caught them when they were being insanely quiet didn’t really matter. At the moment, all that mattered was figuring out how to explain this to Aunt Cass.

“Uh hey Aunt Cass,” Tadashi said lamely. Not really sure what else to say, as it was kinda obvious she was staring at their ears, tails, and eyes.

She just continued to stare at them, seriously unnerving her nephews. “Aunt Cass, please talk to us,” Hiro begged his aunt. He was very scared of her freaking out or something worse happening.

She stayed quiet, before calmly walking over and placing her hands on Tadashi’s second ears atop his head. He was nervous, and his ears and tail flick in response to that. Aunt Cass gasped softly when she felt the second ears move beneath her fingertips. She continued to move her hands, and soon gently began to rub the ears.

Tadashi froze for a second when she started to rub his ears, before suddenly purring softly at the nice sensation of his ears getting rubbed. It was strange, and at the same time nice. Soon Aunt Cass stopped rubbing his ears, before going over to Hiro and doing the same, but the younger Hamada had purred louder than his brother. Gaining the attention of Mochi, he had been sleeping on the couch at the time. The calico stared at the brothers, before simply going up and rubbing against their legs gently. The calico apparently didn’t care too much about the brother being part cat now.

“How did this happen?” Aunt Cass asked once she was done rubbing Hiro’s ears.

Tadashi explained about Hiro’s introduction to his group of friends, and then later about Fred’s invention. He told her they didn’t remember anything when they were taken over by basic instincts right after their transformation. Once he was done explaining, she told them to head up to their room for the night, she needed to think about this.

**BH6-BH6-BH6-BH6**

As they made their way up to their bedroom, Hiro stripped into his pajamas, as did Tadashi. But once he was done, Hiro sat on his bed as Tadashi placed Baymax’s charging station next to his bed. He turned around and saw that Hiro was curled up in a ball on his bed, he wasn’t sleep, he just stayed curled up on his bed.

“Hiro,” Tadashi whispered when he saw his otouto curled up on the bed, his tail wrapped around his legs.

The younger Hamada didn’t move his body, but his ears twitched, letting his brother know that he heard him. “Hiro, are you okay?” Tadashi whispered as he slowly made his way over to his prone baby brother. He sat down next to his baby brother wanting to just hold him and make all of his pain go away.

Hiro whimpered, “Did you mean what you said?” Tadashi was confused for a moment from where he was sitting. But then he remembered what had happened to them inside the lab when the others had left. He had told Aunt Cass they didn’t remember, but that was so far from the truth, they remembered everything. What they had done, and what he had told his baby brother as their instincts finally calmed down and they came back to their senses.

Tadashi was silent for another moment, before wrapping his arms around his baby brother and whispering into his new feline ears, “Yes. I meant every word, I love you otouto. More than brothers, you’re my world, you’re my everything, I don’t know what I would do if I lost you.”

Hiro trembled, before rushing over and curling into his big brother’s arms. Tears were streaking down his face, but he was so happy, his Nii-chan loves him the same way he loves him. Hiro started to purr gently in happiness as he cuddled into the arms that were holding. Both brothers smiled and after a short while they fell asleep on Hiro’s bed together both their tails and ears out for the whole world to see.

But as the brothers slept, they didn’t know that something strange was happening, all that mattered, was that they had each other and no one was going to separate them.

**BH6-BH6-BH6-BH6**

The next day, Hiro and Tadashi could smell the bacon and eggs their Aunt was making them downstairs. They both got ready and headed downstairs where their aunt was waiting for them. Hiro was wearing one of his red t-shirts and a pair of blue cargo shorts, while Tadashi was wearing a green dress shirt, with his brown cardigan over it, and a pair of black pants.

They made their way downstairs and into the kitchen where their Aunt was finishing up breakfast, the bacon, eggs, juice, and tea all on the table. “I’m surprised you two are down here so early,” Cass commented as she started to take a seat at the table, Tadashi and Hiro soon following suit.

“We smelled the bacon and eggs and got up after that,” Hiro told her.

“Thank you for making breakfast Aunt Cass,” Tadashi smiled. And Hiro nodded in thanks as well.

As the family ate their early breakfast, it was around six in the morning, and the café wasn’t due to open for another hour and a half, at seven thirty. Once they were done and the dishes were washed, Aunt Cass spoke up for the first time since the boys came down for breakfast.

“Tadashi, Hiro,” the brothers paused and turned around to face their aunt. Their ears twitched gently and their tails lashing softly behind their backs, the movements betraying their nervous feeling. “I’ve thought long and hard about what you told me last night, and well. We might not be able to change you back, but you’re still my boys. Well you’re my Anthro boys now,” she smiled at them. She walked over and pulled them both into tight hugs.

Hiro and Tadashi both trembled as they hugged their only living family back just as tight as she hugged them. They had been subconsciously worried that their Aunt wouldn’t love or accept them with their new features. But now that they knew she would truly always love them, it was the best news they’d ever heard.

“Now, where are you two going today?” She asked them.

Before Tadashi could tell her they weren’t going to go anywhere, the elder Hamada’s phone started to go off, several times at once. Signifying that he was getting numerous texts at the moment, opening his phone he saw four new texts on his phone, one from each of his friends.

They all said the same thing: **_“Get down to the lab; we have a serious problem here!”_**

“What’s going on?” Hiro asked when he saw the worried look on his brother’s face.

“We’re needed at the lab, apparently something happened, and the gang didn’t say what was wrong.” Tadashi told his brother, and he soon went upstairs to grab their shoes.

Aunt Cass watched Tadashi run upstairs, and turned to her younger nephew and told him, “Be careful, and don’t let anyone see your ears and tail, until you get to the lab okay?”

Hiro just smiled up at his worried aunt. “Don’t worry Aunt Cass, we’ll be fine. And no one is gonna see our ears and tails, okay.”

“Come on Hiro, we gotta get going.” Tadashi told his brother and handed him his socks and shoes. His own already on, and soon the two of them soon made their way downstairs to where Tadashi’s moped is and made their way over to SFIT.

It didn’t take too long to get there, since there wasn’t that much traffic, they headed up to the lab. “You think they’re okay?” Tadashi asked Hiro as they finally arrived at the double doors to the robotics lab space.

“Probably, they weren’t in the explosion yesterday, and we’re the only Anthros in the world.” Hiro stated. Tadashi nodded and opened the door, only to freeze, along with Hiro. “I think I should change that last statement.”

**Notes for the Chapter:**

> The reason why things are a little fast paced here, is because I'm skipping over an important scene that will be brought back in the future chapters as a flashback. Most likely in the next few chapters that'll explain why Hiro and Tadashi confessed their love to each other so early.


End file.
